Flame-resistant polyolefine compositions



United States Patent 3,331,797 FLAME-RESISTANT POLYGLEFINE COMPOSITIONS Kurt Kopetz and Fritz Baxmann, Marl, Germany, assignors to Chemische Werke Huls Aktiengesellschaft, Marl,

Germany, a corporation of Germany No Drawing. Filed Feb. 12, 1964, Ser. No. 344,244 2 Claims. (Cl. 260-285) Due to their ready flammability polyolefines such as polyethylene, polypropylene and polyisobutylene cannot be used as such in the construction and other fields in which difiicultly flammable materials are required. It has been attempted, therefore to render polyolefines flame resistant by additions of chloroparafiines in conjunction with antimony trioxide. satisfactorily flame resistant products are however not obtainable by such additions if the amount of the addition is sufliciently small that other essential properties, especially strength are not unfavorably affected. The great disadvantage of chloroparafline additions lies in the fact that these compounds, even at relatively low temperatures, tend to liberate hydrogen chloride which attacks the machines used in working and forming the composition. The amount of addition required to give a relatively satisfactory flame resistant 'polyolefine is, in any case, more than It is not feasible to add suflicient acid acceptor to compositions containing such a high content of cholorparafline to effect an adequate stabilization.

The use of nucleus bromine substituted aromatic compounds as disclosed in e.g., German Patents Nos. 1,103,020, 1,123,823, 1,127,582 and 1,135,653 brought about a decisive improvement particularly in the avoidance of the dilhculties associated with the use of chloroparafl'lnes.

The testing of the material in the form of plates with respect to flame resistance, self-extinguishment and burning is carried out in two ways as follows:

(1) DIN 4102, page 1 4 plates having the dimensions 1000 x 190 x 3 mm. are supported vertically and in a chimney-like arrangement at right angles to each other and hung in a shaft furnace. Air is passed upwardly through a sieve bottom. Flame is generated by a ring burner having 36 nozzle openings so that the flame strikes the inner surfaces of the plates. The length of the flame is about 250300 mm. After 11 minutes of the flame treatment the burning of the plates must extinguish immediately or in a short time and at least 15% of the plates must remain undamaged.

2 ASTM D635-56T A test piece having the dimensions 127 x 12.7 x 3 mm. is supported at an angle of 45 to its horizontal axis. It is then flamed with a Bunsen burner having a diameter of 5 mm. and with a flame about 12 to 13 mm. long with the tip of the flame just reaching the lower end of the test body. The flaming time is 2 to seconds. If the sample does not continue to burn after removal of the flame it is classified as non-burning by this test. If the sample continues to burn after the removal of the flame but not beyond the 4 inch-markin it is classified as selfextinguishing by this test. If the test piece continues to burn after removal of the flame it is classified as burning by this test.

In the DIN test the burning conditions are such as to correspond to a fire storm, that is, very high temperatures which are increased by the heat of combustion of the sample itself and by the chimney arrangement of the test pieces. Under such conditions only such additions are effective as are eflective at relatively high temperatures. Such compounds are for example the above mentioned aromatic bromine compounds. Aliphatic chlorine compounds are completely useless under these conditions because the decomposition temperature of this type of compounds is very low. The addition of stabilizers does not change this situation. In general it can be assumed that the flaming of differently burnable polyolefines first forms hydrogen chloride which can stop or interrupt the chain reaction of the burning. This action in most cases is increased by antimony trioxide.

The course of the combustion is quite different in the ASTM test process. Here a relatively small flame is used and the mass and energy content of the test body is small. Under these conditions it can be expected that added flame-proofing material having a relatively high decomposition range cannot be efiective since the burning temperature of the synthetic resin body does not at all or only to an insuflicient extent aflect the addition material.

There is a strong technical interest in the provision of an addition or addition mixture which is effective under all practically occurring burning conditions and is equally efiective in both test methods.

It has now been found that flame resistant polyolefine mixtures which contain from 5 to 20% by Weight of nucleus brominated aromatic compounds, 2 to 10% by Weight of chlorinated paraflines and 2 to 9% by Weight of antimony trioxide are especially useful.

Suitable polyolefines for use in the compositions are polyethylene, polypropylene, polyisobutylene and the solid mixed polymers of the corresponding monomers. The polyolefines may contain the usual additions of fillers, colors, lubricants, and/ or stabilizers.

Suitable nucleus brominated aromatic compounds that are to be incorporated into the mixtures in amounts from 5 to 20% preferably from 5 to 12% and especially from 5 to 9% by weight, based upon the polyolefine content of the mixture, are the aromatic compounds containing at least three bromine atoms in the nucleus, of the general formulae R1 R1 R10 9 I I I I I I R4 R5 Ru 1 and R: R1 R10 Re I I I I I I I R4 Ra Ra R7 (9 in which R to R stand for hydrogen, bromine, chlorine, methyl, straight chain and branched chain alkyl and alkenyl groups having from 2 to 4 carbon atoms and the.

, so many of R to R standing for bromine that they together with any other bromine atoms attached to an aromatic nucleus in the molecule amount to at least 3 bromine atoms that are bound directly to an aromatic nucleus. Examples of the values of X are the methylene, ethylidene, propylidene, dimethylmethylene, ethylene, trimethylene, vinylidene, vinylene and allylidene groups. The compounds should contain a total of from 50 to 85% by weight of bromine; from to 30% by weight of this bromine may be substituted by chlorine. The distribution of the halogen atoms on the aromatic ring is optional.

Examples of nucleus halogenated diaromatic com pounds are the halogenation products of dibenzyl, dimethylbenzyl, diethylbenzyl, benzyltoluene, dibenzyltoluene, benzylmethyl-benzylbenzene, diphenylpropane, diphenyls and their mixtures. These compounds need not exhibit any particular stoichiometry. On the contrary it may be advantageous to use mixtures of compounds just as they are produced by halogenation of the named starting materials or mixtures thereof without fractionation or separation in any manner. These mixtures of compounds which a-re mostly of oily or colophony-like consistency contain different numbers and different arrangements of the halogen atoms and generally have less tendency to crystallize than pure compounds. This facilitates the working up of the polyolefine mixtures.

Diaromatic or aromatic-aliphatic ethers containing at least three nucleus substituted bromine atoms of the following formula may be used. In this formula R stands for anarornatic ,group that may be brominated and/ or chlorinated or a bromodiphenyl ether, tribromomonochloride diphenyl ether, tribromodichloride-diphenyl ether, tribromotrichloride-diphenyl ether, and tetrabromodichloride-diphenyl ether. The halogen atoms of these diaromatic ethers can be distributed at random on the aromatic rings. Examples of suitable aromatic-aliphatic ethers are the 2-ethylhexyl-, n-octyl, nonyl butyl-, dodecyl-, and 2,3-dioxypropyl ethers of tribromophenol, tribromomonochlorophenol and 7 tribromodichlorophenolr Also nucleus brominated, multinuclear aromatic amines may be used which contain from 50 to 85% by weight of halogen of which 50 to 85% by weight is bromine and from 0 to 30% byweightis chlorine and which contain at least 3 bromine atoms per molecule bound to an aromatic'ring. These compounds may contain a total of from 1 to 4 straight chain or branched chain alkyl groups having'from 1 to 4 carbon atoms which may contain OH groups, substituted on the aromatic rings and possibly also on the nitrogen atoms. Examples of suitable nucleus brominated multinuclear aromatic amines are the corresponding halogenation products of diphenylamine, a-naphthylamine, B-naphthylamine, 1,l-dinaph-- thylamine and 1,2-dinaphthylamine. In the bromination it may be advantageous to substitute a part of the bromine by chlorine provided that at least three bromine atoms are bound to an aromatic ring and the total bromine content of the molecule is at least 50% by weight. The halogen in excess of three bromine atoms per molecule may occupy any desired position. It is especially advantageous to use the crude halogenation products which generally are mixtures .of isomeric compounds of different halogen contents. The crude halogenation mixtures are generally compatible with the polyolefines as chemically homogeneous compounds.

Another group of suitable compounds'are the 2,4,6-tribromoanilines of the formula in which R and R stand for hydrogen, acyl groups or alkyl groups having from 1 to 6 carbon atoms and R and R stand for hydrogen or alkyl groups having from 1 to 6 carbon atoms. This group of compounds includes 2,4,6-tribromoaniline itself as Well as 2,4,6-tribromoaniles substituted in the nucleus and/ or on the nitrogen such as 2,4,6- tribromoacetanilide and 2,4,6-tribromolauroylanilide.

Suitable chloroparaflines are the chlorinated straight chain or branched chain or cyclical parafiines having a chlorine content of from 40 to 80%, by weight, preferably 50 to The chlorinated parafiines are used in amounts within the range from 2 to 10%, preferably 2-5%, by weight, based upon the polyolefine.

Antimony trioxide is used in amounts within the range from 3 to 10%, preferably 48%, by weight, based upon the polyolefine.

The components can be mixed with the polyolefine singly in any order or all together and incorporated in I known manner. The resulting mixtures are formed or molded in known manner.

It is surprising that the small additions of chlorinated paratfines which alone are not efiective by any test method so activate the aromatic, nucleus-substituted compounds that they are effective even at low burning temperatures.

The small amounts of chlorinated paraflines used may be" stabilized with the commercially available stabilizers as is customary in the working up of polyvinyl chloride, suflicient stabilizer being used so that at the temperature necessary for working up the polyolefines no corrosion of the machine and molds will results from the splitting off of hydrogen chloride.

The claimed mixture exhibits not only the expected but Ex. Test on the Test According Observation plates to ASTM D635 1 100 polyethylene (mol. wt. about 40,000), 10 pentabromo- Standing Self-extinguishing- Dripping material continues burning monochlorodiphenyi ether, antimony trioxide. for some time. 2 100 polyethylene (mol. wt. about 40,000), 7 pentabromo- Not standmg Burning Dripping material continues burning.

monochlorodiphenyl ether, 5 antimony trioxide. 3 100 polyethylene (mol. wt. about 40,000), 3 chloroperafiine do do Do.

(chlorine content 70%), 5 antimony trioxide. I 4 100 polyethylene (mol. wt. about 40,000), 7 pentabromo- Standing Not burning Dripping material extinguishes immonochlorodiphenyl ether, 3 chloroparaifine (chlorine mediately. content 70%), 5 antimony trioxide. Y 100 polypropylene (mol. wt. about 300,000), tribromo- Almost Standing" Burning Dripping material burns a short time.

acetanilide, 5 antimony trioxide. 100 polypropylene (mol. wt. about 300,000), 4 chloro- Not standing -do Dripping material continues burning.

parafline (chlorine content 70%), 5 antimony trioxide. 100 polypropylene (mol. wt. about 300,000), 4 chloro- Standing Not burning Dripping material extinguishes imparafiine (chlorine content 70%), 9 tribromoacetanilide, mediately. 5 antimony trioxide. 8 100 ethylene-propylene-mixed polymer (mol' wt. about Not standing"... Burning. Dripping material burns a short time.

50,000), 8 nucleus brominated dibenzyl-toluene-benzylmethylbenzyl-benzene mixture (bromine content 04%), 4 antimony trioxide. 9 100 ethylenepropylene mixed polymer (mol. wt. about -do ..do Dripping material continues to burn.

50,000), 4 chloroparafiine (chlorine content 65%), 4 antimony trioxide. 10 100 ethylene-propylene mixed polymer (molt wt. about Standing Not burning Dripping material extinguishes im- 50,000), 7 nucleus brominated dihenzyl-tolueuebenzyl Inediately. methylbenzylbenzene mixture (bromine content 64%), 4 chlgroparaifine (chlorine content 70%), 4 antimony trioxi e. 11 100 polyethylene (mol. wt. about 90,000), 10 halogenated ...'do Burning Dripping material burns for a time.

diphenylamine (bromine content 62%), chlorine content 3%), 5 antimony trioxide. 12 100 polyethylene (mol. wt. about 90,000), 10 halogenated .-do ,l. Not burning Dripping material extinguishes imdiphenylamine (bromine content 62%, chlorine content mediately. 3%), 4 chloroparaffine (chlorine content 70%), 4 antimony trioxide. 13 100 polyethylene (mol. wt. about 90,000), 4 chloroparafiine Not standing- Burning Dripping material continues to burn.

(chlorine content 70%), 4 antimony trioxide. 14 100 polybutene-l, 10 pentabromomonochlorodiphenyl do Sell extinguishing. Dripping material burns {or a time.

ether, 5 antimony trioxide. 15 100 polybutene-l, 7 pentabromomonochlorodiphenyl Not standing. Burning. Dripping material continues to burn.

ether, 5 antimony trioxide. 16 100 polybutene-l, 3 chloroparaifine (chlorine content .....do .do Do.

70%), 5 antimony trioxide. 17 100 polybutene-l, 7 pentabromomonochlorodiphenyl Standing Not standing Dripping material extinguishes imother, 3 chloroparamne (chlorine content 70%), 5 antimediately. mony trioxide.

In Examples 4, 7, 10 and 17 similar results are obtainable by using bromineor chlorine-bromine-substituted dibenzyl, dimethyldibenzyl, diethyldibenzyl, benzyltoluene, diphenyl, diphenylmethane, diphenylethane, diphenylpropane, diphenyl ether, diphcnylamine or naphthylamine having from 3 to 8 bromine atoms and from 1 to 3 chlorine atoms per molecule as the aromatic bromine-chlorine containing compound.

We claim:

1. A flame resistant polyolefine composition consisting essentially of a normally solid polyolefine, from 2 to 10% by weight, based on the weight of the polyolefine of a chlorinated parafiine, from 2 to 12% by weight based on the weight of the polyolefine of antimony trioxide and from 5 to 20% by weight based on the weight of the polyolefine of a nucleus brominatcd aromatic compound containing at least three bromine atoms per molecule bound directly to an aromatic nucleus and containing from 50 to 85% by weight of halogen of which from 50 to 85% by weight is bromine and from 0 to by weight is chlorine, at least by weight of the molecule being bromine, said compound being selected from the group consisting of (1) compounds of the formulae 1 1 l io Ra Ra RI l I R4 Ra Ra R1 and 2 1 I -io R9 R: X R

I R4 Ra a R1 in which R to R each stands for a member selected from the group consisting of hydrogen, bromine, chlorine, methyl, straight chain and branched chain alkyl and alkenyl groups having from 2 to 4 carbon atoms and the benzoyl group which may be substituted by at least one halogen selected from the group consisting of bromine and chlorine, X stands for a member selected from the group consisting of divalent saturated and unsaturated aliphatic groups which may be substituted by at least one member selected from the group consisting of bromine, chlorine and aromatic groups; (2) compounds of the formula in which R; stands for a member selected from the group consisting of aromatic groups that may contain at least one halogen selected from the group consisting of bromine and chlorine, straight and branched chain alkyl groups having from 2 to 12 carbon atoms and which may contain hydroxyl groups and R to R each stands for a member selected from the group consisting of hydrogen, chlorine and bromine; (3) multinuclear aromatic amines containing from 1 to 4 alkyl groups each having from 1 to 4 carbon atoms which may contain OH groups; and (4) compounds of the formula 7 in which R; and R each stands for a member selected from the group consisting of hydrogen, acyl groupsand alkyl groups having from 1 to 6 carbon atoms and R and R each stands for a member selected from the group consisting of hydrogen and alkyl groups having from 1 5 to 6 carbon atoms.

2. A flame resistant polyolefine composition as defined in claim 1 in which the nucleus brominated aromatic compound contains from 50 to 85% by weight of br'omine and the chlorinated parafline contains from 40 to 10 80% by weight of chlorine.

3 References Cited UNITED STATES PATENTS 2,962,464 11/1960 Feild 26028.5 3,075,944 1/ 1963 Wick. 7 3,093,599 6/ 1963 Mueller-Tamar.

3,250,739 5/ 1966 Sauer.

MORRIS LIEBMAN, Primary Examiner.

' JULIUS FROME, Examiner. 

1. A FLAME RESISTANT POLYOLEFINE COMPOSITION CONSISTING ESSENTIALLY OF A NORMALLY SOLID POLYOLEFINE, FROM 2 TO 10% BY WEIGHT, BASED ON THE WEIGHT OF THE PLYOLEFINE OF A CHLORINATED PARAFFINE, FROM 2 TO 12% BY WEIGHT BASED ON THE WEIGHT OF THE POLYOLEFINE OF ANTIMONY TRIOXIDE AND FROM 5 TO 20% BY WEIGHT BASED ON THE WEIGHT OF THE POLYOLEFINE OF A NUCLEUS BROMINATED AROMATIC COMPOUND CONTAINING AT LEAST THREE BROMINE ATOMS PER MOLECULE BOUND DIRECTLY TO AN AROMATIC NUCLEUS AND CONTAINING FROM 50 TO 85% BY WEIGHT OF HALOGEN OF WHICH FROM 50 TO 85% BY WEIGHT IS BROMINE AND FROM 0 TO 30% BY WEIGHT IS CHLORINE, AT LEAST 50% BY WEIGHT OF THE MOLECULE BEING BROMINE, SAID COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF (1) COMPOUNDS OF THE FORMULAE 